WASHINGTON AP) - Computer failures related to the Year 2000 technology problem could extend well beyond New Year's Day, President Clinton's top Y2K expert said Thursday. Although John Koskinen predicted a national "sigh of relief" in the early hours of Jan. 1, he also anticipates scattered electronic failures over the first days, weeks and even months of the new year. Koskinen, chairman of the President's Council on Year 2000 Conversion, said some failures may not become obvious until the end of January, the first time after the date rollover that consumers review their monthly bank statements, credit-card bills and other financial paperwork.